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Could someone please explain the difference between “brilliance” and “scintillation” to me? They seem like the same thing but from the study material they are different. Thanks!


I believe that scintillation is light reflected off of the facets externally, the flat polished facet surface reflects light. Brilliance is the light reflected internally from the facets back to the observer, that is how I read the text. AE6ST


Thanks ae6st, I took a day off and let my brain cool down and came up with this:
The definitions I got were these -

Brilliance-" the surface and total internal reflection of light" and in book it said that brilliance is aka lustre and reflectivity.

Scintillation -“The sparkles of reflected light produced when the when the light source or the gemis moved”

so now that i go back, perhaps brilliance is when you just look at it and scintillation is when you move the ring around and it sparkles.

That’s what it sounds like to me now that I stepped away from it for a while. Please tell me if you think its wrong and thank you for your input.



Scintillation is a product of motion. It requires movement of the diamond, the light source, or the eye of observer in order to produce sparkle. A key component is dynamic contrast within the diamond which creates an on/off effect among the facets.
What attracts most people to diamonds is the snap, crackle and pop of the scintillation of a diamond. That is why most fine stores are very smart to intall perfect lighting over their diamond cases to bring out this in the diamond. Notice in most of the ads for diamonds these days has them on a turn stile as the diamond puts on a show. A high performance diamond of ideal cut under correct lighting will cause the customer to gasp. It’s a wonderful sight.


Brilliance is the reflection of light. A poorly cut diamond is considered “dead” Some will refer to these as “frozen spit” It is not advised to use these terms when selling your diamonds. There is a home for all diamonds. But if you have a diamond which exhibits superior Brilliance, you will find it easier to sell, as the diamond practically sells itself

Here is a cute video for a quick explanation


Hi, Dianacap and everyone else. It looks like diana did better after a break than I did after my study time…which shows that a short break, getting away from the problem for awhile does really help the mind and learning process. AE6ST, Mike


Hello everyone,

Just an FYI that IGS is working on a glossary, which we think will be really helpful for our gemology students.